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eZ80 CPU - writeframeofmind.biz

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<strong>eZ80</strong> <strong>CPU</strong><br />

User Manual<br />

54<br />

INDM<br />

Input and Decrement HL<br />

Operation<br />

Description<br />

(HL) ← (C)<br />

B ← B – 1<br />

C ← C – 1<br />

HL ← HL – 1<br />

The contents of the C register are placed on address bus (7:0) and zero on<br />

address bus (23:8). The byte at this I/O address is read into the <strong>CPU</strong>. The<br />

contents of HL are then placed on the address bus and the byte is written to the<br />

memory address specified by the HL register. The B, C, and HL registers are<br />

decremented. The Z Flag is set to 1 if the B register decrements to zero.<br />

ADL mode affects operations with the HL register. ADL mode may be<br />

overridden with the .S or .L suffix.<br />

Condition Bits Affected<br />

S<br />

Z<br />

H<br />

P/V<br />

N<br />

C<br />

Not affected.<br />

Set if B-1 = 0; reset otherwise.<br />

Not affected.<br />

Not affected.<br />

Set.<br />

Not affected.<br />

Mnemonic Operands ADL Mode Cycles Op Codes<br />

INDM — X 5 ED, 8A<br />

INDM.S — 1 6 52, ED, 8A<br />

INDM.L — 0 6 49, ED, 8A<br />

UM007701-1100

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